T I N 



It consists of 



Two equivalents of sulphur 

 One equivalent of tin 



471 



T I N 



32 



58 



Equivalent . . 90 



Phosphuret of Tin is readily formed by adding phosphorus 

 to the melted metal ; it is of a silvery-white colour, am 

 soft enough to be cut with the knife. After fusion it crys- 

 tallizes on cooling ; when thrown upon a red-hot coal, the 

 phosphorus burns. This compound does not appear to havi 

 been accurately analyzed; but when phosphuretted hydro- 

 gen is made to act upon a solution of protochloride of tin, 

 a terphosphuret is formed, which is readily oxidized by the 

 action of the air. 

 It consists of 



Three equivalents of phosphorus 48 

 One equivalent of tin . . 58 



Equivalent . . IOC 

 I'ulides rif Tin. To prepare the protiodide, two parts of 

 granulated tin are to be heated witn five parts of iodine ; 

 the resulting iodide is a red translucent substance, very 

 fumble, soluble in water, and volatile at a high tempera- 

 ture. 

 It consists of 



One equivalent of iodine . 126 



One equivalent of tin . 58 



Equivalent . . 184 



The Periodic!/' nf Tin is formed by dissolving the 

 hydrated peroxide of tin, precipitated by an alkali from 

 the solution of the bichloride, in hydriodic acid ; it forms 

 crystals of a silky lustre, which are resolved by boiling 

 water into peroxide of tin and hydriodic acid. 



X A niiiri't i if Till. When tin is fused with selenium, 

 they combine with the evolution of light. The compound 

 formed is a spongy mass, of a grey colour and metallic 

 lustre ; when heated, selenium is expelled and peroxide of 

 tin remains. 



OXISALTS OF TIN. 



Protonitrate of Tin is formed by dissolving either the 

 metal or the protoxide in dilute nitric acid ; a yellow un- 

 cry^allizable solution is obtained ; by exposure to the air 

 it absorbs oxygen, and peroxide of tin is precipitated. 

 It is probably composed of 



One equivalent of nitric acid . 54 

 One equivalent of protoxide of tin 66 



Equivalent . . . 120 



fprnitrate of Tin. When tin is acted upon by strong 

 nitric acid, the peroxide formed remains entirely insoluble 

 in the acid ; to procure the pernitrate it is best to cause the 

 hydrated peroxide to dissolve in dilute nitric acid. The 

 solution is colourless and yields no crystals ; when diluted 

 or heated, it is rendered turbid. 



Xiiijihiiti-f i if Tin. By boiling excess of tin in sulphuric 

 acid, a solution is obtained from which colourless acicular 

 ..Is of sulphate of tin are deposited. When, on the 

 other hand, tin is boiled in excess of sulphuric acid, or 

 hydrated peroxide of tin is dissolved in the acid, persul- 

 phate of tin is obtained in solution, but it cannot be made 

 to crystallize. 



Carbonate of Tin. When carbonate of potash is added 

 to protochloride of tin, a white precipitate is formed, which, 

 supposing it to contain carbonic acid while moist, loses it 

 during washing and drying ; it appears therefore that a 

 permanent carbonate of this metal is not attainable. 



I'hoxphates of Tin. When phosphate of soda is added to 

 a solution of protochloride of tin, an insoluble white pre- 

 cipitate of protophosphate is obtained ; the perphosphate, 

 also an insoluble colourless precipitate, may be procured 

 by adding the phosphate of soda to a solution of perchlo- 

 nde of tin. 



Having described the principal and best known oxisalts 

 of tin, we shall mention the characters of the salts of tin, 

 as given by Dr. Thomson ; they are as follows : The proto- 

 salts of tin are white, and the solutions of them are usually 

 colourless ; their taste is astringent and metallic, and 

 highly disagreeable ; when in solution, they rapidly absorb 

 oxygen, and are converted into the corresponding per- 

 salts. 



When a plalc of lead or zinc is put into a solution of 

 tin, it is thrown down in the metallic state. Ferrocyanide 



of potassium occasions a white gelatinous precipitate when 

 dropped into these solutions, and sulphuret of potassium 

 occasions a coffee-brown precipitate in the salts of the 

 protoxide of tin ; but neither gallic acid nor infusion of 

 galls occasions any precipitate. When chloride of gold is 

 poured into solutions of protoxide of tin, a purple-coloured 

 precipitate falls. A solution of potash throws down a 

 white precipitate, which dissolves in excess of tHI alkali 

 If the solution be boiled, a black powder falls, which is 

 metallic tin ; while a compound of peroxide of tin and 

 potash remains in solution. Ammonia throws down a 

 white precipitate, not soluble in excess of the alkali. 



ALLOYS OF TIN. 



Most of the malleable metals are rendered brittle by 

 alloying with tin ; it combines readily with potassium and 

 sodium, forming brilliant white alloys, which are less 

 fusible than tin ; the potassium alloy burns readily when 

 it contains more than one-fifth of potassium. With 

 arsenic it forms a metallic mass which is whiter, harder, 

 and more sonorous than pure tin. With antimony tin 

 forms a white, hard, and sonorous alloy. Bismuth forms 

 with tin an alloy which is more fusible than either of 

 the metals separately, a mixture of equal weights melt- 

 ing at 212 ; this compound is hard and brittle. Copper 

 and tin form alloys which are well known and highly use- 

 ful ; they are bell-metal and bronze. With mercury tin 

 readily amalgamates, and the compound is used for silver- 

 ing mirrors. With iron tin forms white compounds which 

 are more or less fusible according to the proportion of 

 iron they contain ; tinplate is of all the alloys of tin the 

 most useful, and the preparation of this and of pewter are 

 the most extensive applications of this very valuable 

 metal. 



TIN, MANUFACTURE OF. Under this head may 

 be noticed, first, the processes required to bring tin into a 

 marketable state, embracing the smelting and refining of 

 the metal ; secondly, the manufacture of tin-ware, or of 

 articles of tin-plate ; and, thirdly, a few of the manufac- 

 tures of compound metals in which tin forms the principal 

 ingredient. The process of TINNING, or of covering plates 

 of iron, the inner surfaces of vessels of iron or copper, &c., 

 with a thin coat of tin, forms the subject of a separate 

 article. 



Smelting and Refining of Tin ; preparation of Block 

 and Grain Tin. The processes by which tin-ores are me- 

 chanically separated from the grosser impurities which are 

 usually found with them, and broken into fragments con- 

 venient for the subsequent operations, are briefly noticed 

 in the article MINING, vol. xv.,. pp. 244 and 245. After 

 being thus reduced to a coarse powder, the ore is roasted 

 or calcined in a reverberatory furnace, until it ceases to 

 exhale arsenical vapours, by which, together with some 

 subsequent processes, it is further cleansed from the admix- 

 ture of foreign matter and prepared for smelting. A very full 

 account of all the processes connected with the prepara- 

 :ion and smelting of tin-ore, as practised about sixty years 

 since, is given in the ' Mineralogia Cornubiensis ' of Pryce, 

 of Redruth ; but, although most of the processes are still 

 performed with little alteration, we have depended more 

 ;br the following account of them upon an extensive 

 article on ' Tin,' in Dr. Ure's recently published ' Dic- 

 tionary of Arts, Manufactures, and Mines,' in which the 

 previous operations of mining are also minutely described. 



The ores of tin raised in Cornwall and Devonshire are 

 always reduced, or smelted, within those counties, their 

 exportation being prohibited ; but this arrangement is 

 stated not to be injurious to private interests, because the 

 vessels which bring the fuel from Wales for the smelting- 

 furnaces return to Swansea and Neath laden with copper- 

 ores. The smelting-works do not generally belong to the 

 proprietors of the mines, but to other parties who pur- 

 chase the ore from them, their value being determined by 

 a kind of assay. When several bags of ore, of nearly uni- 

 ibrm quality, are taken to the smelting-works, a small 

 sample is taken from each, and these samples, after being 

 tended together, are mixed with about four per cent, of 

 ground coal, placed in an open earthen crucible, and 

 leated in an air-furnace until the ore is reduced. As the 

 \irnace is made very hot before the crucible is introduced, 

 ;he assay is finished in about a quarter of an hour ; after 

 which the melted metal is poured into a mould, and the 

 drossy substances which remain in the crucible are pounded 



